Ethernet cable works on XB1 but not on 360

So about a month back I had just an XBOX 360 and on the college campus that I live on we can't connect our game consoles to WiFi, only wired. My 360 worked with ethernet all last year and for a few weeks this semester. I took advantage of an amazing XB1
deal and when I got the new console in the mail I decided the two of them would share the same cable, just switch back and forth when I need to. For a few days this worked, I think I only used my 360 once or twice since I was exploring the new One.

Then one day the 360 wouldn't connect to the network with the cable plugged in. I tried my best to find an answer online and spent hours trying to figure it out (since the cable works with my One). Finally I assumed my 360's ethernet port was blown, and
I hesitantly sent it to Microsoft, spending eighty bucks. About two weeks later I get a new replacement (probably refurbished) console in the mail, and the same problem is occurring. I'm absolutely dumbfounded over how the same issue could take place on two
different 360s but on an XB1 there is no issue. I'm upset that I just wasted 80 bucks for my problem to not be resolved, and if its not Microsoft's fault, I at least would have liked some honesty about whether or not there was REALLY an issue with my old 360.
I doubt they'd send me a refurbished console that had the same faults my old one was sent in for, so does anyone have any idea what the problem could be?

Note: This isn't a complaint about Microsoft's repair service, I just want the issue resolved so I can get back on my 360 games.

:)

 

Network Sharing

So there's no way I can connect an ethernet cable from the 360 to the xb1 and get online on the 360?

 

Can't Connect Xbox 360 Slim Wireless Or Xbox 360 Wired Console

Ok, try a different Ethernet cable and a different port on the router, even try the slim on that Ethernet cable (as a test)

If a different Ethernet cable and/or router port does not help or putting the Slim in the place of the older 360 does work on that Ethernet cable then the Xbox Ethernet port is damaged I'm afraid and will have to be repaired by Microsoft.